The present invenion relates to vehicular brake systems and more particularly to such systems operated by hydraulic fluid.
Most automobiles include an hydraulic brake system for applying brake power to each wheel of the vehicle when a pedal is pressed. In addition, an emergency/parking brake system having a mechanical linkage to only two of the wheels is also provided. The conventional mechanical linkage system has several disadvantages. It must be manually set after the vehicle has been brought to a stop. As a result, it is often neglected and drivers rely on the transmission to prevent the vehicle from rolling. The transmission does not provide secure braking power and is generally only applied to two wheels. Also, unattended children often shift the transmission into the neutral position. Even when the emergency brake has been set, it may be released by a child or by an automobile thief who has "hot wired" the engine to bypass the ignition switch. And even if the emergency brake were controlled by the ignition key as suggested by Wright in U.S. Pat. No. 3,937,295, the mechanical linkage, usually wires, could be easily severed by the thief to release the brakes. The emergency brakes are independent of the hydraulic brakes of the vehicle, and malfunctioning emergency brakes do not affect operation of the vehicle.
The primary object of this invention is to provide a vehicle emergency/parking brake which does not suffer from the above disadvantages of conventional brakes. The brake disclosed is automatically set when the ignition switch is turned to the off position and the brake cannot be readily removed without affecting operation of the vehicle. Further, the parking brake is applied to all four wheels to prevent towing of the vehicle and to provide more braking power. The additional braking power is often needed when a vehicle is parked on a hill or when the parked vehicle is struck by a moving vehicle.
A further advantage of the present invention is that any fluid which leaks from the conventional hydraulic brake system is replaced with operation of the auxiliary brake system of the present invention.
The auxiliary brake system is an easily connected addition to the conventional hydraulic system.